RIVELLA LAB: PROJECTS
Gene transfer for the cure of ß-thalassemia and sickle cell anemia. Preclinical and clinical studies demonstrate that it is possible to treat ß-thalassemia by lentiviral-mediated transfer of the human ß-globin gene. However, all these studies did not address whether lentiviral vectors will correct the synthesis of hemoglobin in erythroid cells irrespective of the different mutations and amounts of endogenous hemoglobin produced. Therefore, clinical trials would greatly benefit from a simple analysis using progenitor erythroid cells to determine the relationship between the number of copies of the lentiviral vector integrated and the total amount of hemoglobins produced. This approach would provide an efficient way to predict the outcome of the gene transfer before the patients undergo a partial or total myeloablation and bone marrow transplant. We have constructed a novel lentiviral gene delivery system that carries the human ß-globin gene and demonstrated that this vector can obtain long-term correction of mice affected by ß-thalassemia intermedia and major. We also characterized these new lentiviral vectors in patient cells in vitro as a preclinical test for potential gene therapy trial, showing correction of the hemoglobin synthesis defect and phenotype. Based on these promising results, we are now testing our new vectors in cells from sickle cell patients in collaboration with by Dr. Deepa Manwani at Montefiore/Albert Einstein Medical center.
Generation of induced pluripotent stem cells for the cure of ß-thalassemia and sicke cell anemia. Recent advances in stem cell biology have demonstrated that it is possible to derive induced pluripotent stem cells (iPSC) from thalassemic or SCD human somatic cells. Furthermore, homologous recombination experiments demonstrated that it is possible to correct the mutated ß-globin gene in iPSC cells derived from patients. In other words, it is now possible to reprogram the patient's own blood cells into stem cells and correct their ß-globin gene. The ultimate goal would be to engraft patients with these corrected iPSC-derived bone marrow stem cells and generate healthy red cells. However, generating corrected iPSCs using the current technologies entails several potential drawbacks, including potential disruption of oncogenes and tumor suppressors and further manipulation of the iPSC clones to correct that mutation in the ß-globin gene. Unfortunately that means that we could theoretically cure the SCD and ß-thalassemia but might cause the patients to develop cancer or other diseases. We propose a novel approach to generate corrected iPSCs that overcomes all of these issues. Furthermore, in order to simplify this procedure, we established a protocol to expand blood progenitor cells from a small amount of blood (~30 mL) to generate curative iPSCs.
Iron metabolism in ß-thalassemia and in hemochromatosis. Progressive iron overload is the most salient and ultimately fatal complication of ß-thalassemia and hemochromatosis. We discovered that the hepatic peptide hepcidin limits iron absorption degrading the iron exporter ferroportin at the level of hepatocytes and macrophages. In ß-thalassemia, ineffective erythropoiesis represses hepcidin, leading to iron overload. Therefore, we hypothesized that increased expression of hepcidin reduces iron burden in ß-thalassemia. In fact, increased levels of hepcidin prevent iron overload and ameliorate the anemia in animals affected by ß-thalassemia. Moreover, we investigated the relationship between erythropoiesis and iron overload in mice affected by hemochromatosis (Hfe-K0). We discovered that the Hfe gene is expressed in erythroid cells and this affects the rate of erythroid cell proliferation and production. We are now investigating the relationship between Hfe, other iron related proteins and the EpoR/Jak2 pathway in erythroid cells. In addition, our findings might also have an important impact on the treatment of this disorder. Patients affected by hemochromatosis require frequent phlebotomies to avoid iron overload. However, we described that in mice affected by hemochromatosis, erythroid cells utilized mainly iron absorbed from the diet rather than the excess stored in the liver. The implications of these findings are that patients, after phlebotomy, might benefit from a low iron diet or use of hepcidin agonists. We are now testing hepcidin agonists as a therapeutic tool in ß-thalassemia and hemochromatosis.
Ineffective erythropoiesis in ß-thalassemia. This project began with the observation that there is an excessive production of immature red cells in patients affected by ß-thalassemia. Our study suggests that erythropoiesis in ß-thalassemia is characterized by enhanced expression of genes that promote cell cycle and survival. Based on these studies we proposed the use of Jak2 inhibitors in ß-thalassemia. We showed that this is extremely effective in limiting ineffective erythropoiesis, splenomegaly and extramedullary erythropoiesis, and it has a positive effect on iron metabolism. Similar data were achieved in mice affected by sickle cell anemia. The future direction of this project is to develop new therapies for the treatment of ß-thalassemia after characterization of genes that are dysregulated in the erythroid tissue.
The role of macrophages in Polycythemia vera and ß-thalassemia. Macrophages represent an important link between erythropoiesis and iron metabolism. They support maturation and differentiation of erythroblasts and clear senescent red cells from circulation, thus recycling iron within the hematopoietic system. However, little is known about the role of macrophages in conditions of altered erythropoiesis like in Polycythemia vera and ß-thalassemia intermedia. Our goal is to study the role of macrophages under condition of expansion of the erythron. Our preliminary data suggest that macrophages have an important function related to the expansion of the erythron. In fact, modulation of their activity leads to profound and beneficial effects in these two important disorders.
Characterization of iron metabolism and erythropoiesis in anemia of inflammation. Hepcidin, through interleukin-6 and BMP2, might be upregulated in many inflammatory disorders, including some forms of cancer. High levels of hepcidin limit iron absorption and sequester iron in the macrophages, leading to reduced red cell production and anemia. This is likely to be associated with production of other inflammatory cytokines that impair erythroid proliferation. To further investigate this process, we generated two models to characterize iron metabolism, erythropoiesis and cytokine production, as well as the role of macrophages in inflammation and anemia. Using the heat inactivated brucella abortus agent, we are studying a sterile model of inflammation that exhibits anemia. Moreover, we are also studying cancer models that exhibit inflammation and anemia to investigate these features during tumor progression.
A-TYPE proanthocyanidins demonstrate selective activity against acute myelogenous leukemia (AML) cells. Acute Myelogenous Leukemia (AML) is a fatal disease where even after strong induction therapy regimens most patients relapse and die of their disease. We have identified that proanthocyanidins found in cranberry extracts display a potent anti-leukemia activity. Many of the reported health benefits of cranberries, including anti−tumor activities and the prevention of urinary tract infections, are associated with a unique class of proanthocyanidins referred to as A−type PACs. An isolation technique was developed to obtain a PAC fraction from Early Black cranberries. Our results suggest that cranberry PACs have potential therapeutic value for the treatment of leukemia due to their ability to ablate leukemia cells while they have minimal effects on normal hematopoietic stem cells. This work is being done in collaboration with Dr. Monica Guzman, Ph.D. in the Dept of Medicine at WCMC.